[Lowfer] Al Loop Conductor?

K2ORS k2ors at verizon.net
Mon Nov 7 21:06:26 EST 2011 

Bill,
      There is a nice online calculator that allows you to calculate Rac for
any frequency if you put in the material properties (resistivity and
permeability, for Copper and Aluminum permeability is 1.0)
http://www.mantaro.com/resources/impedance_calculator.htm

(Scroll down the page about 1/2 way).

Cheers,

Warren



----- Original Message ----- 
From: "Bill Ashlock" <ashlockw at hotmail.com>
To: <lowfer at mailman.qth.net>
Sent: Monday, November 07, 2011 8:31 PM
Subject: Re: [Lowfer] Al Loop Conductor?


>
> Interesting detail, Warren! Things are looking even better for Aluminum
> (Now if we could only solder to the darn stuff with simple equipment :).
> That WAS 100Khz, so we need data for higher frequencies, before we can
> fall in love with it. I'll see what I can find. Now I'm wondering what it
> is about an element that defines its skin depth. (??)
>
> Bill
>
>> From: k2ors at verizon.net
>> To: lowfer at mailman.qth.net
>> Date: Mon, 7 Nov 2011 20:04:37 -0500
>> Subject: Re: [Lowfer] Al Loop Conductor?
>>
>> Bill,
>>       I received the following comment from Rik Strobbe:
>> "Hi Warren,
>>
>> aluminium has a higher resistivity (28x10^-9 Ohmmeter) than copper
>> (17x10^-9
>> Ohmmeter) but it has a larger skin depth (Al = 260 um, Cu = 210 um at
>> 100kHz).
>> That makes an Al wire only 33% worse than a Cu wire of the same diameter.
>> Regarding mechanical strength it might be a good idea to inforce this by
>> a
>> steel wire support.
>>
>> 73, Rik  ON7YD - OR7T"
>>
>> ----- Original Message ----- 
>> From: "Bill Ashlock" <ashlockw at hotmail.com>
>> To: <lowfer at mailman.qth.net>
>> Sent: Monday, November 07, 2011 7:58 PM
>> Subject: Re: [Lowfer] Al Loop Conductor?
>>
>>
>> >
>> > Hi again Scott,
>> >
>> > Thank you for the positive comments on my loop experiments. I am
>> > looking
>> > forward to doing a similar study of loop performance variables at 500K,
>> > particularly with loops supported and in full contact with trees.
>> >
>> > I got to thinking about your use of #2 ga Aluminum and checked out my
>> > Loop
>> > Article #2 which has a comparison of various conductors types (185K). I
>> > show the Rac of #2 copper to be close to that of RG-8 and was wondering
>> > if
>> > you or anyone else has had the chance to compare these Racs. I would
>> > think
>> > that just the difference in Cu vs Al would amount to a 1.7X increase in
>> > Rac for the #2 Aluminum...But considering you are running an incredible
>> > 50
>> > Amps I realize this is a totally different ball game. Maybe it should
>> > be
>> > called "The Battle of the Loop Conductor Meltdowns" :)
>> >
>> > Best regards,
>> >
>> > Bill
>> >
>> >> Date: Sun, 6 Nov 2011 18:05:49 -0800
>> >> From: sthed475 at telus.net
>> >> To: lowfer at mailman.qth.net
>> >> Subject: Re: [Lowfer] Al Loop Conductor?
>> >>
>> >> Greetings Bill
>> >>
>> >> I have only built one single conductor (#2AWG AL) loop thus far and it
>> >> works very well and have no data to offer comment on Rac of CU vs
>> >> AL...
>> >> Thanks to your efforts much of my design effort was based on your very
>> >> good papers on the topic and designing a tuner that could handle in
>> >> excess of 50A key down.
>> >>
>> >> Using indirect means of approximately determining the impedance of my
>> >> loop revealed a better than expected performance when compared to
>> >> modeled solid circular conductor.  I'm making an educated guess
>> >> (hypothesis) that this is related to the greater surface area of the
>> >> stranded conductor itself.  Perhaps this is something you care to
>> >> study
>> >> in greater detail?
>> >>
>> >> My qualitative opinion of this being the 'perfect' loop conductor was
>> >> based on my wallet not being greatly lightened to purchase the
>> >> conductor
>> >> and my back not overly strained to carry it away and install.  I
>> >> believe
>> >> this is an engineering compromise that I feel favours the
>> >> sensibilities
>> >> of most operators (price and weight vs a slight compromise on the
>> >> performance CU would provide.)  As I have alittle more leeway on 2200m
>> >> compared to the Lowfer band this compromise MAY amount to something
>> >> negligible and be overwhelmed by the other advantages.  Maybe not so
>> >> on
>> >> Lowfer?
>> >>
>> >> During operation, it appeared to perform well enough that for me there
>> >> was no interest in delving into the nuisances as JA7NI awaited...
>> >> Particularly since I could achieve my 1W EIRP with ease now.
>> >>
>> >> Is my overall hypothesis correct? I'll leave that to the experts such
>> >> as
>> >> yourself to explore and explain.
>> >>
>> >> 73 Scott
>> >>
>> >>
>> >>
>> >> On 11/6/2011 5:06 PM, Bill Ashlock wrote:
>> >> > Hi Scott,
>> >> >
>> >> > Considering the exchange of info on this topic I conclude we have
>> >> > the
>> >> > density and DC resistivity of Cu vs Al pretty well in hand but what
>> >> > about the Rac of Cu vs Al? Has anyone measured the Rac of aluminum
>> >> > conductors... and at different frequencies? Also we shouldn't forget
>> >> > the 'proximity effect' and the 'skin effect' when using large
>> >> > diameter
>> >> > conductors. I proved at 185K that the reduction in Rac was quite
>> >> > small
>> >> > when the conductor diameter was increased. Even separate insulated
>> >> > conductors twisted together netted little improvement over a single
>> >> > conductor and only when the spacing was approximately 1" was there a
>> >> > worth-wide improvement. Twisted, insulated, conductors do not define
>> >> > Litz cable. The interweaving needed is much more complex than this.
>> >> >
>> >> > Bill
>> >> >
>> >> >> Date: Fri, 4 Nov 2011 21:07:43 -0700
>> >> >> From: sthed475 at telus.net
>> >> >> To: lowfer at mailman.qth.net
>> >> >> Subject: Re: [Lowfer] Al Loop Conductor?
>> >> >>
>> >> >> Hi Warren
>> >> >>
>> >> >> My 100m perimeter LF loop is constructed of similar AL wire.
>> >> >> You'll
>> >> >> find it the PERFECT loop conductor as it's much lighter and cheaper
>> >> >> than
>> >> >> copper.  The conductivity issue is not that big of a deal as my
>> >> >> conductor had much better conductivity than calculated.  I figure
>> >> >> this
>> >> >> is due to the increased surface area based on the stranded nature
>> >> >> of
>> >> >> its
>> >> >> construction.
>> >> >>
>> >> >> Another nice feature of neutral supported cable type conductor is
>> >> >> the
>> >> >> insulation is tough and will have been tested by UL/CSA or similar
>> >> >> to
>> >> >> have a dielectric withstand in excess of 3KV.  No arcing here ever.
>> >> >>
>> >> >> Just ensure you use a suitable compound on any joints to mitigate
>> >> >> oxidation.
>> >> >>
>> >> >> 73 Scott
>> >> >> VE7TIL
>> >> >>
>> >> >>
>> >> >> On 11/4/2011 5:29 PM, K2ORS wrote:
>> >> >>> Hi,
>> >> >>>       I am considering using Aluminum service drop wire (3/0
>> >> >>> gauge)
>> >> >>> as a
>> >> >>> conductor for an LF transmitting loop. I know that the
>> >> >>> conductivity
>> >> >>> is not
>> >> >>> as good as copper but it weighs so much less that I can use a
>> >> >>> larger
>> >> >>> diameter conductor.
>> >> >>> Has anyone tried this? How would it hold up when flexed by the
>> >> >>> wind ?
>> >> >>> Other
>> >> >>> thoughts?
>> >> >>>
>> >> >>> 73 K2ORS
>> >> >>>
>> >> >>> ______________________________________________________________
>> >> >>> Lowfer mailing list
>> >> >>> Home: http://mailman.qth.net/mailman/listinfo/lowfer
>> >> >>> Help: http://mailman.qth.net/mmfaq.htm
>> >> >>> Post: mailto:Lowfer at mailman.qth.net
>> >> >>>
>> >> >>> This list hosted by: http://www.qsl.net
>> >> >>> Please help support this email list:
>> >> >>> http://www.qsl.net/donate.html
>> >> >>>
>> >> >> ______________________________________________________________
>> >> >> Lowfer mailing list
>> >> >> Home: http://mailman.qth.net/mailman/listinfo/lowfer
>> >> >> Help: http://mailman.qth.net/mmfaq.htm
>> >> >> Post: mailto:Lowfer at mailman.qth.net
>> >> >>
>> >> >> This list hosted by: http://www.qsl.net
>> >> >> Please help support this email list: http://www.qsl.net/donate.html
>> >> >
>> >> > ______________________________________________________________
>> >> > Lowfer mailing list
>> >> > Home: http://mailman.qth.net/mailman/listinfo/lowfer
>> >> > Help: http://mailman.qth.net/mmfaq.htm
>> >> > Post: mailto:Lowfer at mailman.qth.net
>> >> >
>> >> > This list hosted by: http://www.qsl.net
>> >> > Please help support this email list: http://www.qsl.net/donate.html
>> >> >
>> >>
>> >> ______________________________________________________________
>> >> Lowfer mailing list
>> >> Home: http://mailman.qth.net/mailman/listinfo/lowfer
>> >> Help: http://mailman.qth.net/mmfaq.htm
>> >> Post: mailto:Lowfer at mailman.qth.net
>> >>
>> >> This list hosted by: http://www.qsl.net
>> >> Please help support this email list: http://www.qsl.net/donate.html
>> >
>> > ______________________________________________________________
>> > Lowfer mailing list
>> > Home: http://mailman.qth.net/mailman/listinfo/lowfer
>> > Help: http://mailman.qth.net/mmfaq.htm
>> > Post: mailto:Lowfer at mailman.qth.net
>> >
>> > This list hosted by: http://www.qsl.net
>> > Please help support this email list: http://www.qsl.net/donate.html
>>
>> ______________________________________________________________
>> Lowfer mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/lowfer
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:Lowfer at mailman.qth.net
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>
> ______________________________________________________________
> Lowfer mailing list
> Home: http://mailman.qth.net/mailman/listinfo/lowfer
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Lowfer at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html

More information about the Lowfer mailing list